Title holders East Bengal moved into the semi-finals of the IFA Shield football tournament, edging past a fighting Tollygunge Agragami 2-1 on Friday.
The day's other match, between Mohammedan Sporting and Kolkata Port Trust, was forced to be stopped 40 seconds before time as violence erupted.
Trouble broke out in the Group B outing at the Mohammedan Sporting ground before the end of injury time after referee Sarat Chandra Singh of Manipur turned down Sporting's demand for a penalty, with the match still goalless.
Hundreds of Sporting supporters barged into the ground and surrounded the referee before the police managed to whisk him away.
The mob then directed its ire on fourth referee Jayanta Chakraborty and three Port players who were all injured.
As Sporting fans continued to abuse the referee and pelt stones, referee Singh left the ground after blowing the long whistle.
Later Sporting general secretary Sultan Ahmed told newspersons that his club would demand a replay.
When contacted, an IFA spokesman said the tournament committee would decide the fate of the match after going through the referee's report.
"As of now, we can only state that the match ended 40 seconds before time," he said.
In the other quarter-final Group A match, Trijit Das put East Bengal ahead in the 31st minute before Manas Das restored parity for Tollygunge in the 61st minute.
East Bengal, who topped Group A with six points, scored the winner through Suley Musah in the 70th minute to ensure a passage into the last four.
Churchill Brothers, who culled five points from their engagements, had already qualified for the semi-finals from Group A.
From Group B, TFA had earlier made it to the semis with five points.
